I have seen many people arguing over new order notification. Foodomaa new order notification only work on WIndows and Android and its not working on iOS. It only work if browser active tab is store Dashboard. What u have to do is enable OneSignal notification and than go site settings in Chrome.
Chrome > Settings > Notification > Foodomaa (your site address)
Here you can customize the notification as per your need. I have chosen a different notification tone for my site and its 1 min long.
Whenever there is new order I get a onesignal notificaion. As my notification tone is 55 secs long so in my case it play the sound for 55 secs.
I hope it help and sorry for my bad English.